1. Field of the Invention
The present invention relates to a lock mechanism of a connector device employed in an electrical unit, for connecting signals.
2. Description of the Related Arts
As a recent development of information processing techniques, an information processing system is constructed in which a computer and a plurality of electrical units are connected to each other. In the system, many cable connector devices are used for transferring information to each of a plurality of information transfer media. In order to arrange many unified circuits in alignment in an electronic apparatus and thereby to simplify the maintenance, detachable units of a plug-in unit system are often used.
In such a processing system or electronic apparatus, the failure of a unit causes the operation inefficiency, data destruction, or the destruction of the whole system. In order to cope with such a state, there is employed a double structure of units in which two identical units are prepared and one of the units automatically starts operating to make it possible for the processing system to continuously operate when the other is failed. In this duplicated structure, there is an advantage In that a unit can be replaced while the system is still in operation so that the maintenance can be performed without decreasing the operation efficiency. On the other hand, there is a problem in that because a unit can be replaced at any time during the system operation, a normally operating unit may be erroneously pulled out from the processing system. In this case, the destruction of data or the system would be caused.
In order to solve the above problems, a connector device in which a lock mechanism is provided for preventing a unit from being erroneously pulled out and a faulty unit can be pulled out only after a control signal is supplied from a host processing system, is disclosed in, for example, JP-A-63-279462. That is, in this apparatus, when recognizing the faulty unit, the processing system switches from the faulty unit to another unit and at the same time unlocks the lock of the faulty unit to enable the faulty unit to be removed for repair.
In a case where the connector device having the above lock mechanism is used for a plug-in unit, the configuration as shown in FIG. 1 would be considered. As shown in FIG. 1, a back panel 200 has a female connector 201 at both ends of which guide pins 202 are provided for guiding the female connector 201 when it is to be engaged with a male connector to be described later. On the other hand, a plug-in unit 203 accommodates a magnetic disk apparatus 204 therein. The male connector 206 mounted on a printed circuit board 208 is provided to a case 205 of the plug-in unit 203 and connected to the magnetic disk apparatus by a cable 209. In addition, guide bores 207 which engage with the guide pins 202, respectively, are arranged in the case 205. Further, an electromagnetic solenoid 201 with a retractable plunger 211 is arranged in the plug-in unit 203. The engagement hole 213 engaging with the plunger 211 is punched in a rail 212 for supporting the plug-in unit 203 mounted on the back panel 200.
The procedure of engagement in the connector device thus configured as described above will be described below.
First, when being installed in the back panel 200, the plug-in unit 203 is guided in accordance with grooves provided on the rail 212 so as to be positioned at a desired position. Then, the guide pins 202 each having tapered tip ends engage with the guide bores 207 in accordance with the guide of the tapers so that the female connector 206 engages with the male connector 201. The plunger 211 of the electromagnetic solenoid 210 of the plug-in unit 203 is accommodated in the case 205 when no power is supplied. However, after the male connector 206 has engaged with the female connector 201, the plunger 211 is inserted into the engagement hole 213 of the rail 212 by activating the electromagnetic solenoid 210 in response to a control signal supplied from the host processing system (not shown) to lock the plug-in unit 203.
Further, the plug-in unit 203 is fixed to the rail 212 by a fixing screw 214. Thus, the plug-in unit 203 is completely installed. Thereafter, the magnetic disk apparatus 204 is supplied with power and set in an operable state.
Next, in a case where the plug-in unit 203 needs to be pulled out for any reason, such as failure or system modification, the magnetic disk apparatus 204 and other processing circuits need to be stopped for reasons such as prevention of data destruction in the magnetic disk apparatus 204 and prevention of damage of the plug-in unit 203 or the processing system. For these reasons, in the plug-in unit 203 of this example, the measures taken to stop operation, such as rotation, are, for example, disconnecting the power supply before the plug-in unit 203 is pulled out and after a predetermined time is elapsed, which is the time required for the rotation to stop, the power supply is disconnected in response to the control signal supplied from the host processing system which draws the plunger 211 of the electromagnetic solenoid 210 from the engagement hole 213 on the rail 212. Thereafter, the fixing screw 214 is loosened and the plug-in unit 203 is pulled out from the back panel 200.
Therefore, only one of the plug-in units designated by the control signal supplied from the host processing system is allowed to be pulled out and erroneous operation, such as pulling out of a normally operating unit, is prevented. As a result of this, data destruction and system destruction can be avoided.
However, since the conventional connector device is configured as described above, the positioning precision for the guide bore and the guide pin as a guide mechanism directing the connector engagement, and the positioning precision for the engagement hole and the plunger of the electromagnetic solenoid of the lock mechanism for maintaining the connector engagement are both required at the same time. That is, in addition to the precision of parts required in the design, the assembly precision is also required when the parts are assembled. Both the positioning precision and the assembly precision over a plurality of connector devices, i.e., a combinational precision, must be maintained because the plug-in unit needs to be replaced when an internal part has failed or the magnetic disk apparatus is to be exchanged with a new one. In a case that these precisions cannot be maintained, a problem is caused in that the engagement of the plunger cannot be performed smoothly, the lock cannot function effectively, or the extraction and insertion of a connector cannot be performed smoothly. Also, there is another problem in that inadequate installation of a plug-in unit and erroneous extraction of a plug-in unit cannot be completely prevented because it cannot be confirmed whether or not the engagement of the connector device or lock is reliably performed. Further, there is still another problem in that a large amount of processing time is required to maintain the combinational precision as described above.